What you need to know about fibre

Fibre is a common word that most of us are aware of and know that we need it in our diet to help prevent constipation. But what exactly is it, where does it come from and what does it do?

Fibre is often linked with preventing constipation, but is this true and how does it help with this? Most people know that it is found in wholegrains and vegetables, but which foods are the best sources?

In this blog, we answer these key questions and provide some ideas on how to consume the optimum amount of fibre each day.

What is fibre and where does it come from?

Fibre is a complex carbohydrate found in plant cells that can’t be digested or absorbed by the small intestine in humans, but is broken down in our large intestine (bowel) by bacteria that use it for food.

The main types of dietary fibre are known as soluble fibre, insoluble fibre and resistant starch. All three are required for a healthy gut and have the following properties:

1. Soluble fibre is found in oats, peas, beans, apples, citrus fruits, carrots, barley and nuts. It dissolves in water to form a gel-like substance and softens stools so they’re easier to pass.

2. Insoluble fibre doesn’t dissolve in the gut and can’t be digested. It is found in wheat bran, brown rice, cauliflower, tomatoes, carrots and nuts and adds bulk to stool to help push it through the digestive system. 

3. Resistant starch is also classed as a fibre because it isn’t digested in our stomach or small intestine, but provides food for the friendly bacteria in our colon. Resistant starch is found in cooked then cooled potatoes and green bananas.

What does it do?

Fibre helps to keep our digestive system healthy and to prevent constipation by adding bulk to our stools, whilst also making them softer and easier to pass. Fibre also helps to promote peristaltic movement of waste products through our intestines, thus helping to support transit time and keep us regular.

Some fibre that is indigestible by humans is used to feed the friendly bacteria in our gut, thus helping to increase the colonies of the favourable species and to control the growth of the unfriendly types, which feed off sugar. These specific fibres are known as prebiotics.

How much do I need to eat each day?

The amount of fibre we require depends on our size and weight. There is a general recommendation of around 30g per day for adults (around 25g for women and 38g for men), but it is worth getting clear on what exactly is right for you.

Children require less than adults – around 15g from 2-5, 20g from 6-11 and 25g from 12-16 year of age.

How do I get my daily servings of fibre?

Again, this depends on the types of foods you are eating and a general principle would be to ensure that you are adding fruits, vegetables and other sources of fibre to every meal. Think about including the following foods to your daily intake:

  • Wholegrains, such as oats, brown rice, buckwheat and wholewheat flour
  • Vegetables – as many as you can each day, including potatoes and including skins where possible
  • Legumes, including beans, pulses, chickpeas and lentils
  • Fruits – again with their skins on where possible
  • Nuts – all sorts of plain unsalted and untreated nuts
  • Seeds – pumpkin, sunflower, sesame, flax and chia seeds are all great options

And be aware of the following…

Make sure you are drinking enough water, as the additional fibre will draw more water into your bowels to maintain stool consistency, thus removing it from your body and potentially causing dehydration.

Chew your food properly to ensure that your food is fully broken down ready to be digested as it reaches your stomach and intestines. 

Sit down to eat whenever possible and take a moment before you start eating to take a few breaths, appreciate what you are about to eat and start the production of saliva, which starts the digestive process (the cephalic stage of digestion).

Increase your fibre intake slowly to help avoid gas and bloating, particularly if you suffer from symptoms of irritable bowel syndrome (IBS). Soaking legumes overnight before you cook them can help to reduce the potential for causing gas and chewing food also helps.

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